


If the Water's Still Flowing

by Sineala



Category: Avengers (Comics), Marvel (Comics), Marvel 616
Genre: Alternate Universe - Merpeople, Avengers Vol. 1 (1963), Fluff, Fluff and Smut, Interspecies Relationship(s), Interspecies Romance, Interspecies Sex, M/M, Plot What Plot/Porn Without Plot
Language: English
Status: Completed
Published: 2019-07-16
Updated: 2019-07-16
Packaged: 2020-06-29 10:15:20
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,106
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19828048
Author URL: https://archiveofourown.org/users/Sineala/pseuds/Sineala
Summary: When a flight test of Tony's new Iron Man suit model sends him plunging into the depths of the Atlantic, rescue comes from the most unlikely of sources. Tony had thought mermaids were fictional, but this man is very, very real. And Tony certainly never expected the merman to be handsome... and the attraction to be mutual.





	If the Water's Still Flowing

**Author's Note:**

  * For [phoenixmetaphor](https://archiveofourown.org/users/phoenixmetaphor/gifts).



> Happy birthday, phoenixmetaphor! It has been great to know you! Here is some mermaid porn!
> 
> For people who are not phoenix, I should probably mention that this was written to accompany a drawing phoenix did of Tony and Mer Steve, uh, getting it on. Sadly, the picture is very NSFW and as far as I know phoenix has nowhere to host it, but I assure you that it's a really beautiful picture.
> 
> This is an AU set in volume 1 shortly after Tony gets his synthetic heart (so, after Avengers #69), but in a universe where Steve has never been an Avenger because, uh, he's a mermaid.
> 
> Beta courtesy of BlossomsintheMist!

The routine flight test should have been just that -- routine. Tony's been Iron Man for a good couple of years now. He knows how to build suits, and he knows how to test them. Other than the fact that the man inside the suit is now operating it with a shiny new synthetic heart rather than a chestplate -- which had reduced the suit weight by a fair bit, actually -- there should have been nothing different.

But this particular model had been giving him a bit of trouble. There's been a transient error in the flight systems that he hasn't quite been able to pin down, or, at least, he hadn't in the lab. It's been doing great here in the practical test. He wouldn't have taken it out for a spin, otherwise. But he'd been okay hovering over the mansion, and so he'd decided to head out east, out to open water. He's past Long Island Sound, over the Atlantic itself, blue sky above him and shining sea below. Distance flight. He's been out here for an hour. The suit has been handling like a champ.

It reminds him a little of the old days, that first team -- him and Thor and Wasp and Ant-Man, after the Hulk had left. There'd been only the four of them, rattling around the mansion, and Tony had pulled all-nighters in the basement, improving the armor again and again, because there were only the four of them to save the whole damn Earth, and he knew that they needed to be ready for anything.

And then an alarm beeps in his ear and Tony is jerked back to reality. His blood goes cold. _Flight error_ , he thinks, and then he feels one of the boot jets cut out. He initiates a restart cycle. It doesn't come back on.

He's wobbly with one boot and both palm repulsors, but he's still airborne. Flying the suit isn't like piloting an airplane. Airplanes are aerodynamic in a way that Tony most definitely isn't. A plane with complete engine failure can be flown like a glider, can still be landed safely. Iron Man with complete flight system failure -- well, he can very much _not_.

He's not going to panic. There's no reason the rest of the suit should fail. There's no reason the boot jet shouldn't restart, any second now.

It's not coming back on.

Something else must be wrong, something must be terribly wrong, some wire shorted, because the sensors are reporting something that isn't even here. Something he can't see. Some kind of unknown energy, the readout says. Energy level rising. Flight error. Flight error.

Through the eye-slits, Tony stares at his outstretched hands, watches both palm repulsors sputter and dim. The flight system alert keeps whooping in his ears. And then the other boot jet dies.

Tony'd like to say that his life flashes before his eyes, but he doesn't actually have time for that.

"Activate emergency beacon!" he shouts, but he already knows that the suit is dead around him.

He's dropping, dropping--

He shuts his eyes. He doesn't want to watch his death coming.

He hits the water. His head snaps to the side, his skull slamming into the helmet, and the world rings around him--

Everything goes black.

* * *

If he'd been conscious after the impact, he might have had a shot. But Tony opens his eyes to find water pouring in the mouth-slit and the eye-slits of his suit, his head throbbing where it slammed into the side of the helmet. He can't breathe. He can't take a breath. It's too late. There's water all around him.

The suit, of course, is dragging him down. He tries to fumble for the releases, but he's clumsy and slow, his lungs screaming for air. The sunlight above is becoming more and more distant.

He's drowning.

He's dying.

He thought it was going to be his heart, and now, after everything--

A hand wraps around Tony's gauntleted wrist -- a man's bare, muscular arm. A swimmer, out this far? Tony can barely see through the eye-slits, but he makes out a halo of golden hair, floating around the man's head. His very own angel.

There's the shadow of shining fins somewhere behind the man, a tail -- they must be falling through a school of fish.

But the man's grip on Tony doesn't falter, and he pulls him up toward the sunlight.

_Oh, thank God_ , Tony thinks, and then he passes out again.

* * *

When he wakes up, there's solid ground under him -- he's still armored up, and he's coughing up water, doubled over, and he doesn't care about his goddamn secret identity right now. He could be on the Jersey shore, surrounded by sunbathers, but he needs the armor off, off, off.

His gauntlets are slick, covered in a tangle of seaweed, and won't stick in the catches. He staggers, falls, creaks; he's on his knees again. Water is lapping at his ankles; he can hear it against the metal of the suit.

"What can I do?" a man asks. His rescuer, still, probably. The man's voice is light, pleasant, a little confused. Not as urgent as Tony expects. Like he doesn't quite understand that Tony can't breathe. "How can I help?"

"Helmet," Tony gasps out. "Off. Emergency-- emergency release." He manages to raise one hand, motion to the depression just under his chin.

The man fumbles clumsily with his helmet, eventually jamming two fingers into the release. The waterlogged mechanism clicks, thank God, and Tony wrenches it off. The helmet bounces as it lands on the rocks and Tony takes a grateful full breath of air. He can get the rest of the gear off later and figure out exactly how screwed he is, but right now he has air, oh, God, air.

He pushes himself upright, to his knees, and turns to take in his rescuer, and--

Dear God, he's _beautiful_.

As far as the general public is concerned, Tony's tried to be circumspect about the fact that his sense of aesthetic appreciation is a little broader than just the fairer sex, but this man-- this man-- God, he's _gorgeous_. The man is still half-submerged in water, but the half that Tony can see looks like some kind of Greek god come to life. His body is fit, muscular, _perfect_. Blond hair is plastered to his head -- darkened and damp now from the water, but Tony imagines it drying gold, sunshine-gold.

Tony wants nothing more than to touch him, and he curses the fact that he's still covered in armor.

The man is staring at him with huge, sky-blue eyes, his reddened lips parted, and to judge by the dazed and dreamy look on his face he's thinking exactly the same thing about Tony that Tony is about him. Tony can't imagine he looks like anything more than a drowned rat right now, but this guy's staring at him like Tony is the most handsome man he's ever seen.

Tony waits for a spark of recognition to come into the man's eyes, waits for him to say _you're Tony Stark and you're Iron Man too_ , but the guy just keeps staring, enthralled. Tony seems to have found the one person in the whole damn world who doesn't know who he is. In either identity.

"Thank you so much," Tony manages to say. His mouth is salty and disgusting. But he's still breathing. "Thank you. You saved my life."

A concerned, worried cast comes over the man's face. "You're welcome," he says. "But I-- I-- I shouldn't have."

In Tony's extensive superheroing experience, this is not what anyone ever says at this particular moment. It's sure not what he says, anyway. What the hell?

"You shouldn't have?"

The beautiful stranger shakes his head. "I-- we're not supposed to-- I shouldn't be talking to you right now. The longer I spend here, the better the chance they're going to figure out what I did."

Tony stretches out a gauntleted hand, trying to pull the man closer, to make him see that he's welcome. "Hey, it's okay--"

"I have to go," the man says, and then he just... dives. Just like that.

He's gone.

Tony has no idea where he's going. It looks like he left Tony on some kind of island, but everything around him is ocean, silver-blue as far as the eye can see. Where the hell is the guy planning to go?

This is really not what Tony was expecting any kind of rescue to be like.

* * *

Tony spends a good fifteen minutes wrenching himself out of the armor -- the water did a number on all the release catches, apparently -- and sets it all out on the rocks to dry, optimistically.

He's really only pretending to be optimistic about it. He knows that the salt water has probably fried literally every system beyond repair.

At least he's got clothes on, underneath. Not much, but an undershirt and boxers are better than nothing, especially if his rescuer comes back. He's really hoping his rescuer comes back, because right now that guy is his only hope for getting home.

His clothes are mostly dry by the time he's done exploring the little island he's on. There's not much to see, because the place isn't much more than a little rocky outcropping. More urgently, for his needs, there doesn't seem to be any food or fresh water.

He sits down on the rock where he arrived, and it's like a sign -- a golden head bobs up from the waves. His rescuer.

"Hi again," Tony ventures.

The man swims closer, almost close enough to touch, if he pulled himself up out of the little wave-tossed pool he's still floating in. He shakes his wet hair out of his eyes and Tony finds himself struck dumb at the man's beauty, watching droplets of water slide down his skin.

And the man's staring back at him, just as enthralled as Tony is, which is ridiculous, because Tony knows he definitely does not look his best right now.

"Sorry about that," the man says, and even his _voice_ is beautiful. "I bought us some time, I think. Warded the area. They're not going to be thrilled with me, but right now they don't know about you and I-- I just had to see you again."

The intensity in his gaze makes Tony, a practiced flirt, go hot all over. This guy-- he wants him, God, he wants him like maybe no one else has. This is so fast. This is so soon. But this guy is so handsome. Anyone would understand, wouldn't they? 

Tony sternly reminds himself that there are more important concerns here. Like getting back to civilization.

He smiles back; it's a real smile, stretching his face wide. He can't not.

"Well, I'm grateful you came back," Tony murmurs, with his best flirtatious look, eyes gone half-lidded, and, yeah, this guy is interested; Tony watches him lick his lips. "But I think right now I've really got to get back home. If you give me your name, I can definitely look you up...?"

"Steve," the man says, instantly, eagerly. "I'm Steve. What's your name?"

He has to know. He _has_ to. But somehow he doesn't.

"Tony," Tony tells him. "Tony Stark."

And, nope, Steve still doesn't get it. There's no sign he's ever heard of him. "Tony," Steve breathes. "I've never met anyone like you."

The way he says it, it's not a line. He honestly means it. He's staring at Tony like Tony is something rare and precious, and not a bedraggled guy sitting here in his underwear surrounded by the remains of his armor.

To hell with it. Maybe civilization can wait just a little bit longer.

"Nice to meet you, Steve," Tony murmurs. He pats the rock next to him. "You want to come up, get acquainted?"

Suddenly shy, Steve bites his lip. "I, uh-- you're sure?"

"Of course," Tony says. "Climb on up."

Steve swims over to the nearest rock and pulls himself up, powerful muscles flexing and rippling in a way that Tony just can't stop staring at and-- holy shit.

The bottom half of Steve... is a fish tail.

"You're," Tony says, stupidly, staring. "You're a mermaid."

"Merman," Steve says, helpfully. "Yes."

He wonders if he's dreaming. He wonders if he's hallucinating.

"You're real," Tony says. His voice is shaking. "You-- you're really real."

Steve's smile is still a little shy, but it's definitely there. "I really am."

Tony had no idea the world had so much wonder in it. He'd thought everything was known, mapped, understood -- and right here, right now, he's sitting on a rock next to a merman.

Steve's tail coils around the rock, fins glistening in the light. Water beads, iridescent and bright, on the scales. Tony thinks this is probably about where an ordinary man would step away, but as far as he's concerned, Steve is still beautiful. He wonders what Steve's tail would feel like, if Steve let him touch it.

"How?" Tony asks, and it's the only question he can manage. "How are you-- How is this-- How has no one else ever--"

"Magic," Steve says, simply, and Tony thinks of all the magicians the Avengers have ever run into. "We don't want humans to know about us. So... no one will know. No one finds out." He bites his lip again. "The mer world isn't, uh. Very happy with your people. With what you do to the oceans. To the world. So we live in the depths, hidden away, where humans will never find us."

"But you're here. And I'm here."

And, sure, Steve's clearly got a thing for him -- but it wasn't like Steve could tell what he looked like when he hauled him out of the water.

Steve half-smiles. "I was out past the glamour, where I shouldn't have been, but I-- I've always been curious." He exhales hard. Tony wonders how he breathes. There's probably more magic involved. "And then I saw you drowning, and I couldn't just let you die. I have to say, you're not what I expected at all."

"First human you've met?"

Steve nods.

"Well," Tony says, "you're definitely the first merman I've met."

Steve's tail curls in the air as he laughs, and Tony tries not to stare. He isn't sure if it's rude to stare. But Steve is just so handsome, the way the scales shimmer, the way his long fins are so thin and delicate, in contrast to the rugged strength of his muscles.

"They always told us humans were monsters," Steve says, softly, almost wonderingly. "I've seen monsters. I've seen krakens and sharks and creatures that only wanted blood. But you don't look like a monster. You don't act like a monster. You seem kind. You seem gentle."

Tony swallows hard and thinks about all the weapons that SI used to make.

"I try to be a good man," Tony rasps. "I haven't always been, but I try. Out in the rest of world I'm an engineer. An inventor. Trying to come up with better energy sources, so we stop ruining the world. I build things." He gestures toward the remains of his suit. "And I'm a superhero. Iron Man. I save people who need help. I-- I try to be kind. I do my best."

Steve is staring at him, awed. "Your best sounds pretty amazing to me."

It's been a long time since Tony's adoring fans have ever rendered him tongue-tied, but Steve has clearly managed to. "I, uh," Tony says. "Thank you?"

"My pleasure," Steve says, and Steve's looking at him again, so hungrily, like he can't get enough of him. Here they are surrounded by water and Steve is just drinking _him_ in.

It's not that Tony's not interested. He's definitely still interested. He wants to feel Steve under his hands, against his body; he wants to see the grace and beauty of him here, where he lives. But he doesn't even know how to begin to ask, and he doesn't know if Steve's reciprocal interest means anything like willingness. Maybe it's not the same for mer... people, anyway. Maybe this is just how they all look at each other.

"What's the mer world like?"

Steve screws up his face in thought, and Tony realizes that he himself probably wouldn't do any better answering the same question about the human world -- how can he expect Steve to explain it to him without any frame of reference?

"I don't really know what to say," Steve says, finally. "We live in caves, mainly. There are always fish about, all sorts of plants. I think it's beautiful. I mean, it's my home. I'd-- I'd show you if you could breathe down there. I'd show you if they'd let me."

"I'd like to see it," Tony returns, and Steve smiles at him again, that gorgeous smile. "What do you do? Is that a silly question? Do you-- do you have jobs?"

"Sort of," Steve says, and it's clearly something that doesn't quite translate well. "I guess you could say I'm a sentinel. I help guard the boundaries of the glamour. Fend off some of the deadlier predators it doesn't work on."

Tony remembers Steve talking about sharks. "You look like you'd do a pretty good job."

He doesn't see a single scar on Steve. Unlike what his own chest looks like, after the heart surgery. It's probably a good thing he still has an undershirt on.

Steve's cheeks color. "I like to think I'm pretty good at it, yeah," he murmurs, and then he lifts his head. "And I suppose if I asked you what the human world was really like, it would be hard to answer, too. I know it can't be like what they tell us. But I don't know what it's like, either." He points at the suit. "Do you all wear metal like that?" 

There's something about his gaze that's still entranced, as he looks at the suit. Even mermen are Iron Man fans, apparently.

Chuckling, Tony shakes his head. "No, that's, uh. That's just me. Because I'm Iron Man. The suit helps me defend people, I guess you could say. That's why I made it."

"Well," Steve says, and Tony can see when he dares to be a little bolder, raising his head to look Tony in the eye, smiling more broadly, "if you don't mind me saying so, it looks very nice."

Okay, that has to be flirting. That has to be. There's no way that isn't flirting. It's a little weird that he's complimenting the pieces of Tony's broken armor, but Tony will take it.

"Why, thank you," Tony replies, offering Steve his best smile. "And I'd show you the human world if I could. You'd like where I live in New York, I think. Right on Central Park. There's all this nature in the middle of the city."

Tony's lost briefly in thought -- could he build Steve a suit? He imagines articulated metal flexing around his tail, repulsors keeping him always hovering. It seems possible. It's a crazy thought, another one of his grandiose dreams. He doesn't even know if Steve would want to go, if he could.

God, he really wants to touch Steve's tail.

"I like that idea," Steve says. "I wish I could see your home too. Maybe-- maybe we're not so different."

Tony knows what he'd do now, if Steve were human. Closeness. The opportunity to touch him, if Steve wants to. But he feels like he should ask first. He doesn't know how Steve will take it.

Tony takes a breath. "Since I'm not getting home anytime soon," he says, "maybe we could... get to know each other better?"

His synthetic heart is pounding. He hopes that when the doctor was telling him about avoiding stress, he didn't mean this.

"I can get you home whenever you want," Steve says, and wow, okay, that's good news. "In an instant. I can cast a basic teleportation spell. But if you wanted, before you left, maybe you could...?"

The words trail off and Steve holds out a hand.

"Yeah?" Tony takes it. His heart is pounding harder. "Like this?"

Steve's grip is strong and firm. Tony imagines Steve's hands on him.

"Like that," Steve murmurs, and he's smiling. "Maybe, if you wanted, more than that?"

"I'd like more than that," Tony admits, and Steve smiles again. "But I don't know what to do. If you were human, I'd take you out to dinner. A show. Entertain you."

Steve laughs a little. "That sounds nice, with the food. We don't really do that. I don't suppose humans court each other the same way, then, at all. If you were mer, I'd... I'd bring you a present. Something shiny, like a pretty shell."

"Oh, we do that too," Tony says, and Steve looks delighted. "There are presents. Not shells, usually, but-- jewelry or... or a watch, maybe, since you're a man."

"What does a watch do?" Steve asks.

"It tells you what time it is," Tony says, and Steve gives him a blank look, like he can't imagine why anyone would need something to do that. And then Tony remembers the way Steve was eyeing the armor. "But I've got shiny things, if you want."

He tips his head in the direction of the armor, and Steve's eyes go wide.

"You can't," Steve breathes, like this is a priceless treasure to him, not because of the millions of dollars of broken transistors and ruined circuitry, but just because it's metal, shining red and gold in the bright, bright sunlight. "For me? Really?"

It's clear that Steve would be just as happy with... well, almost anything shiny, but this is what Tony has. He can spoil him. Steve doesn't even realize how much he's spoiling him. It's kind of sweet.

"Absolutely," Tony says. "With all the water in it, it's no good to me, but, well, it seems like you might enjoy it. A nice guy -- uh, mer -- like you? I can't imagine wanting to give it to anyone else."

Steve smiles... but then his face falls just a little. "But humans, they don't... swim for each other? That's what I'd do, to show you I was grateful, and to show you I liked you, and to-- to---" his face is reddening, a little-- "well, we do it to show off, really. To show how much we-- we want someone. But you can't breathe underwater, so I can't show you properly." Now he's looking distressed, his face twisting in discomfort. Like he thinks he can't match what Tony is giving him. Which as far as Tony is concerned is ridiculous. There has to be some way to show Steve he's worth it.

Ha. Tony is an engineer and he can goddamn well improvise.

He watches Steve's tail curl again around the base of the rock, flexing a little differently this time, like Steve's running through all the motions in his courtship dance in his head even if he can't actually do them.

"If you swam for me," Tony ventures, "it would be so I could see how beautiful you were? So I could see your-- your strong tail? Your pretty fins?"

He isn't sure if it's okay to call Steve _pretty_ , but Steve nods, shy and eager at the same time.

"And if I liked how you looked," Tony presses, "what would we do? Would I touch you? Would you touch me?"

Steve nods again. They're still holding hands. Tony strokes the side of Steve's wrist. Steve's skin is still damp, of course, but warm and soft, and God, Tony wants to know what the rest of him feels like.

"So if I tell you I already think you're beautiful," Tony murmurs, "would you want me to--"

"Do you want to touch my tail?" Steve blurts out, at the same time.

Tony's pulse spikes. Dizzy, blood rushes through his head. He's still not quite sure he's not dreaming. All of this feels unreal. "You'd let me? Is it-- is it okay?" 

He can't quite figure out how to ask what it means. The mer world probably doesn't conceive of intimacy in baseball metaphors but it sounds like at least a second-base kind of thing to Tony.

Smiling, Steve is nodding, again and again -- and then he takes Tony's hand and settles it on his hip, or what would be his hip. Tony's hand spreads over the iridescent scales of Steve's tail. It doesn't feel sharp, like he was expecting, or cold and slimy. Steve is warm under his hands, warm and a little slick, like Tony could just slide his hands all over him. The fin at Steve's waist is soft, delicate, and when Tony brushes a fingertip over it, Steve shudders.

Steve is breathing hard, dark-eyed, and, yeah, Tony is going to guess that this is doing something for him. Tony can feel the blood in his body rush lower. Steve is really into it and, well, that's doing a lot for Tony. Plus, maybe it's a little weird, but, well-- Steve really is beautiful.

"You like it?" Tony asks, half out of sheer curiosity and half because he wants to hear Steve praise him. He's not exactly noble. "You like that?"

"I like that," Steve breathes.

Tony, ever the scientist, has more questions. "Is it sensitive? All the time?"

"I-- oh, mmm, I like that," Steve says, as Tony rubs his hip again. "Not more than anything else. But if-- it's someone you, uh, someone you want to mate with, it feels pretty good wherever they're touching. Usually we'd do this a bit before -- oh, right there, perfect -- really getting into it."

Maybe they're not really that different, then. "Humans do that too," Tony says. "Maybe with even fewer clothes than I'm wearing, if you're interested in that. And some kissing, of course. Lots of kissing."

Steve tilts his head to the side. "What's kissing?"

Tony's brain nearly screeches to a halt. But then he thinks about how kissing probably isn't all that much fun underwater. If they don't come up to the surface that often, they wouldn't have invented it. It's sad, but it makes sense.

"One of my favorite things," Tony says, smiling at him. "I can show you, if you'd like."

"Sure!" Steve says. His smile is like sunshine.

Tony steps in as close as he can, leans in, gets their heads on the same level. Steve is blinking at him, curiously, like he has zero expectations for what Tony is about to do. Tony puts his other hand on Steve's shoulder, slides it up Steve's neck, tangles his fingers in Steve's hair. Their lips meet, awkwardly, and Steve makes a noise that is soft and surprised.

"This is kissing?" Steve asks, against Tony's mouth, drawing back a little. "You bite my face?" He sounds more than a little dubious. His expression is quizzical.

Tony can't help laughing, because he's never really thought of it like that before. "I suppose it's like biting. Not really with teeth, most of the time," he adds. "Unless you like teeth. Some people do." Steve doesn't seem to be one of them.

"It feels... nice." Steve sounds like he's trying to decide how he feels about it. "I think I'd like it if you did it again. I like--" he motions to Tony's face-- "the hair. It's soft. Your mouth is soft, too."

Huh. Maybe mermen don't grow mustaches.

If Steve can still put a coherent thought together, Tony is definitely doing it wrong. "It's one kind of kissing," Tony says. "There's more than this, if you want."

Steve wraps his arms around him and clutches him close. That's a yes.

Tony gently licks across Steve's lips, figuring that Steve will probably like this more the wetter it is. And when Steve's mouth opens and he moans, Tony slips his tongue in Steve's mouth and Steve just... goes wild for it, surging up against Tony's mouth, groaning and gasping, holding him tighter. It's messy and lacking all of Tony's usual finesse, but he thinks maybe Steve likes it better that way.

When Tony breaks the kiss, Steve is panting, and staring at him, dazed, like Tony has shown him untold new wonders. Tony savors the heady rush of being able to make Steve feel this good.

"Wow," Steve breathes. "That feels-- that feels--"

Tony kisses Steve again, lightly. "Glad you liked it."

"Is there more?"

It's time to figure out just how far they're going to go. Steve's been talking about _mating_ like that's the destination he has in mind, and Tony -- okay, Tony is definitely up for that, dear God, his body is informing him that he is definitely up for the direction that this is heading. But it would be good to figure out if they're on the same page, first.

"Well," Tony says, "if we were going to, uh, mate, this would probably be about the point in time where the clothes would start coming off."

Tony's not wearing much anyway, but Steve hooks a finger in the neck of Tony's undershirt and inhales sharply. like the idea of getting to see Tony naked is the most exciting thing he can possibly imagine. This is clearly doing a lot for him. Somehow. Steve is definitely already naked, but Tony can't possibly guess how the rest of this is going to work. He supposes they'll find out.

"I've never, uh," Steve says, shyly. "I've never seen a human take off their clothes."

"I imagine the top half's pretty much the same," Tony says, and he tells himself sternly not to worry about all the goddamn scars from the heart surgery, and he leans back and yanks his undershirt off over his head in one motion before he can change his mind.

And Steve's still looking at him just the same way, awe and desire reflected in his gaze. He reaches out a hand, tentatively, stopping an inch from Tony's chest.

"You can touch me," Tony tells him.

Steve does. He doesn't fixate on the scars, as Tony was expecting, but his fingertips stroke the hair on Tony's chest like he's never met someone with chest hair before. Maybe mermen don't have that either. It feels weirdly nice, actually, like a kink Tony had no idea existed; Tony doesn't think he's ever met anyone who cared.

"I like this," Steve says, curling Tony's chest hair around his finger. "This is-- this is different. Like a seal, but not as much. We don't have hair like this. It's so soft." And then his thumb smooths over the edge of one of the scars, cautiously. "Were you in a fight?"

Was he ever. "Sort of," Tony says. "I've been in a lot of fights. But that's from surgery." Steve mouths the unfamiliar word. "Uh. A kind of... healing?"

"I fought a shark last month," Steve tells him. "Our healers, they have spells for scarring." He half-smiles. "I thought the other mer would think less of me if I had a bite on my ribs, you know? But now I'm looking at you and I think maybe it doesn't make a difference. You're still-- you're still--" He breaks off and smiles. "You're like no one I've ever met, but you're gorgeous."

Steve's hand slides down Tony's stomach, following the trail of Tony's body hair.

"You're very brave," Tony tells him, because he thinks even he'd draw the line at fighting sharks.

Steve smiles. "You save the world, you said. So you're brave too."

Steve's fingers are playing with the waistband of Tony's boxers. Tony thinks maybe Steve doesn't realize he's teasing him. Tony's cock twitches and hardens, and he tries not to impatiently rub himself up against Steve's hand, but, God, just a little lower, please, please.

"You want me to take these off?" Tony asks. His voice is only a little strangled.

Steve nods fervently.

Here goes nothing. Tony stands up and kicks his boxers off. When he looks up again, Steve is staring wide-eyed at his half-hard cock, and, okay, maybe they're going to need to communicate a little more because Steve just looks completely _dumbfounded_. Dumbfounded and kind of extremely turned-on, which is a weird combination but Tony will take it.

"Uh," Tony says. "Okay. I'm guessing that wasn't what you were expecting?"

Steve jerks his head up and meets Tony's eyes. His face is suffused with red. "I, uh. Yes. No. I mean, it... looks about the same, but... your genitals are just _hanging out there_?"

"Yes?" Tony says, confused. "Where else are they supposed to be?"

Steve gestures at himself and Tony's not sure what he's supposed to be looking at because there's nothing there, where everything should be. He's just flat. "Inside, of course," Steve says, like it should be obvious. "There's a pouch. You take them out when... you're ready to mate."

Huh. Tony can't say that doesn't sound like a convenient arrangement, but that's sure not what nature has done for humanity.

"Nope," he says. "This is it. This is how humans work. If you're a guy. I mean, mostly we wear clothes, but, yeah, it's all hanging out there." Steve is still staring at him. "Is-- is that a problem?"

"No, uh," Steve says, and now he's furiously red. Tony wonders if he ever sunburns. "It's just like you're-- you're going around all the time all _ready to mate_ and I, uh." He licks his lips.

"And you like that thought?" Tony ventures.

Steve nods again, still blushing. "I-- I like it a lot."

"Well," Tony says. "I'm not exactly _ready to mate_ all the time, to be honest. Not ready quite yet, anyway. I, uh, need some stimulation first. Like touching, or rubbing, or-- oh, God--"

He doesn't finish his sentence, because that's when Steve wraps his hand around his cock. Steve's fingers are smooth, his grip a little unsure at first, but rapidly growing more confident as Tony trembles and braces himself against Steve's shoulder to try to stay upright, and, God, if Steve doesn't stop he's going to come in about ten seconds. His balls are aching with need, his cock leaking pre-come over Steve's hand, and Steve is staring at him, enthralled. Tony takes a breath and manages to put his fingers on Steve's wrist, stilling him.

Steve looks up. "Am I doing it wrong?" He sounds concerned.

"You're doing it very, very right," Tony assures him, breathlessly. "If you keep doing that I'm going to come, very quickly. I just thought you might want to know."

"Oh!" Steve says, and he looks flattered, a little smug smile curling over his lips. "That's not so different, then. We do that too, sometimes, the rubbing. You want that? More of that?"

"Sure," Tony breathes, because frankly he's out of his mind with lust and he can't really see how anything else is going to work. "Sure, please, yes, anything."

And then Steve's smile turns devious. "Do you want to rub up against my tail?"

Overwhelmed by desire, Tony can't say anything. His mouth falls open. He remembers the softness of Steve's body against his fingers and it's all too easy to picture how it would feel against his cock, slick and warm. He pictures his own come spattering the sheen of Steve's scales and the thought alone is nearly enough to push him over the edge.

"If you don't want to," Steve says, his face falling, and that's when Tony realizes he hasn't actually said _yes_. "That's all right. I understand it's very different from what you're used to--"

God, no. He can't let Steve think that.

"I want it so much," Tony gasps out. "No one ever has, right? So let's try."

Smiling in relief, Steve pulls him closer and kisses him. It's more of a nuzzle, but still -- they're learning so much about each other. Score one for interspecies friendship. Interspecies whatever-this-is.

Finding a position that works is a little undignified. Steve is still sitting on the rock outcropping, because he can't exactly move more onto dry land, and eventually Tony manages to straddle him. They can't kiss without Steve losing his balance, but Steve has his big hands braced on Tony's waist, holding him steady; Tony gets a hand on Steve's shoulder and another hand wrapping around the back of Steve's neck both to keep himself from falling and to get the angle right, and, yeah, yeah, this is going to work.

Tony gives an experimental thrust; their heads tipped down, they both watch his cock slide along the smooth bright warmth of Steve's slick tail, over his shimmering scales, and, yeah, oh yeah, oh, God, this is _definitely_ working.

It's not going to take him long. Tony knows that; hell, he's known that since the moment he saw Steve. And this is clearly how Steve wants it, so Tony lets himself rut against Steve's soft tail, warm against his cock, as shameless as he wants to be. There's no one else out here to see them, and Steve-- well, Steve clearly wants to see it all.

Steve's gaze drifts from Tony's cock up his chest to his face and back down again, transfixed, like he wants to watch everything and remember it forever. His grip on Tony's hips is steady, urging him on; he catches the rhythm of it, moves with him, helps Tony grind up against him.

"You're so beautiful," Steve says, and when Steve says it it feels like he's saying something true, like he's looking at who Tony really is; he's never seen the artifice. "You're so beautiful like this, Tony."

Gasping, Tony throws his head back and shuts his eyes, letting Steve see him, all of him. He's not sure Steve can hear him over the sound of waves breaking against the rock they're on, but Steve just holds him tighter and it's perfect. He can feel his release rising in him like another wave, ready to break.

"I'm going to--" Tony groans. "I'm going to come, can I-- can I come on you?"

Steve's hands clench on Tony's waist and Steve moans like he's the one getting off here. "Please," Steve says, like he thinks he should be the one begging for it. "Come on my tail, please, I want to see you come on my tail--"

And that's all it takes. Tony's gone. He's shaking and coming and Steve's holding him through it as the pleasure rises and crests and Tony's come spatters white and hot over Steve's beautiful scales.

He half-leans, half-falls forward, tipping his head against Steve's shoulder, but it's all right, Steve has him, Steve has him and he's holding him tight as Tony pants against his damp skin. The world is warm and bright and when Tony looks up, Steve is smiling at him, and Tony can't remember feeling anything this good in ages. He's more relaxed than ever. For all that it feels like it could be a dream, Steve feels like the most real person that he's ever been with, the only one who's seen the real him.

It feels like flying: terrifying and wonderful, all together.

"Is that good?" Tony asks, and then Steve lets him go with one hand so he can drag his fingers through Tony's come, smearing it wetly across his scales, and God, Tony wishes he could come again.

Steve's still smiling. "You were so lovely," he murmurs. "You looked like you enjoyed that very much."

Tony nods. "I really did." He pauses, but it has to be okay to ask this, doesn't it? "Can I return the favor?"

"I'd really like that," Steve says, gamely, but there's apprehension in the way his forehead is wrinkling. "I just-- I've never done it out of the water, and I'm not sure I can..."

Tony wonders if this is maybe the mer equivalent of jerking off with your non-dominant hand. "Well, it won't hurt anything to try, right?"

Steve nods, and then his hand is smoothing over his tail, right where his cock would be if he were human. He pushes aside a row of scales that Tony didn't realize wasn't solid; there's a line of flesh there, a little pouch, and then, well, Steve is pulling his cock out. It looks pretty close to human, but wetter -- it's glistening with something viscous. Tony can feel his mouth watering.

He wonders how Steve feels about fellatio; it's probably a little advanced. Best to be simple, for the first time.

He wonders what it says about him that he's already hoping for a second time.

Steve looks up at him, nervously, his hand still lightly gripping his cock. "Is this okay?"

"This is _wonderful_ ," Tony assures him. "Can I touch you?"

Steve smiles gratefully and nods, and Tony reaches out for him.

The texture is different, somehow smoother and wetter, like he's using the world's best lube. Tony likes it; he likes the sight of Steve's cock sliding through his fist, framed by the scales of his tail and Tony's drying come: an obscene and fantastical sight. But then he looks up and Steve is making a face that isn't quite a grimace and that's not good.

Tony stops. "Steve? Am I doing it wrong?"

Steve shakes his head and flushes again. "No, you're good. It's not you. I just-- I think I need to be back in the water to do it. It feels too dry. Sorry."

"Not a problem," Tony says. "We can get back in the water."

Steve gives him a look. The same dubious look he'd had when he'd thought kissing was biting. It's kind of cute.

"I can actually swim," Tony says. "Just not when I'm trapped in a broken suit of armor. Besides, you're not going to let me drown."

Steve looks around them, at the waves still crashing against the rock. "It's a little calmer around the other side of the island," he says. "There's an inlet there, if you want to come down."

"See you there," Tony says.

When he stands up, Steve grins and flips backwards, gracefully, into the water. Tony can see him just under the surface, sunlight and the shapes of the waves playing off his skin. His tail breaches the water once. He's-- God, he's so beautiful.

Tony hurries around the other side of the island to find Steve waiting, as promised, in a little inlet. The water is calmer, like Steve had said, barely lapping at the sides of the rock, and Steve smiles as Tony lowers himself down.

"So how does this work?" Tony asks, as he treads water. "Do you want me to swim with you? I can hold my breath for a bit--"

But Steve shakes his head. "No, that's okay. I think I'll be fine if I can just keep the bottom half of me underwater. And I--" he bites his lip-- "I was thinking, maybe, if you wanted to do that kissing thing again, if it's not too much trouble--"

God. Steve wants him to kiss him and touch him. Tony's having so many brand-new fantasies and they're all coming true.

"I'd love to," Tony assures him.

He ends up braced against the smooth rock wall, his shoulders against the rock, one hand wrapped around Steve's head to pull him close, the other on Steve's cock. Steve is pressing him up so he doesn't sink, and it's weird, but it works. Tony kisses him and kisses him, messy and wet, the way Steve seems to like it. Steve's mouth is slack against his, letting Tony just take him and take him and take him.

He gets his hand working on Steve's cock, a rhythm that's even smoother and slicker than before, and, yeah, this is how Steve likes it.

"Harder," Steve gasps. "Oh, please, like that, but harder--"

He doesn't know if Steve means his mouth or his hand but he tries both, and Steve is trembling against him, trembling so hard that Tony wonders if he's come and he just missed it, but Steve is gasping at him, glassy-eyed, and Tony realizes he's right on the edge.

"I need," Steve says, pulling away from the kiss, and he clearly can't even think anymore. "I need-- I'm almost-- I'm sorry, I just need-- how long can you hold your breath?"

Tony can barely think, himself. "Thirty, forty seconds, maybe?"

"Okay," Steve says. He's still shaking. "Breathe in?"

Tony nods, takes the deepest breath he can, and then Steve pulls him under. Tony opens his eyes to see Steve, beautiful in the bright water, arching back and then wrapping around him. His tail coils around Tony's legs. From the way he does it, it seems like a reflex, and, God, it all feels so good. They can't kiss like this but Tony can keep touching Steve, so he does, his fingers tight on Steve's cock.

Steve shudders and opens his mouth soundlessly, and his tail wraps around Tony even tighter as he comes, his cock spurting a hazy cloud of liquid.

Steve is beautiful like this, familiar and strange and the same time. He's still shaking, and then he uncoils himself and stretches back and Tony can see him smile.

And then Steve is dragging him up out of the water again so Tony can breathe, and after they both have a few seconds to put themselves back together, Steve kisses him first, this time.

"That was amazing," Tony says. "Thank you."

Steve looks at him like he's clearly the crazy one here.

"No, thank you," he says.

"No, seriously," Tony says. "That was-- so beautiful, watching you. And when you grabbed me at the end, with your tail wrapping around me--"

Steve flushes. "Sorry," he says. "That's, uh, that's instinct."

"Please don't apologize," Tony tells him. "I liked it. I'd like it if you did it again."

Steve smiles shyly, and then Tony feels the whisper-soft touch of Steve's fins brushing past his calves. "Like this?" he asks, as Tony shivers with the sensation of it. No other human has ever felt this. He's so lucky.

"Exactly like that."

Tony smiles back and this-- this is happiness.

* * *

They both know, of course, that Tony has to go. Tony climbs up, puts his clothes -- such as they are -- back on, and Steve floats there regarding him.

"I'm going to miss you," Steve says.

"Yeah," Tony says. "Me too."

There has to be a way. Somehow, there has to be a way to come back. Maybe he could get a message to Namor? He bets Namor knows all about these people. But right now, he can't think about that. He has to go. He has to get home. He has a team. He has a company. People miss him.

"So how does this spell of yours work, exactly?" Tony asks.

"Well, I'm not a very good magician myself," Steve says. "I don't know the theory. I just know how to cast it. We use it on predators. It-- it knocks them out and it sends them home. Wherever that is."

"Sounds good," Tony says, except it kind of doesn't, of course. He doesn't want this to be over.

Steve's gaze is sad. "You ready?"

"I'm ready," Tony says. "You want another kiss first?"

"You bet," Steve says, and he pulls himself out of the water. Their lips meet.

And then Steve whispers a word of magic and the world goes black again.

* * *

Tony wakes up face-down in sand. Water is lapping at his toes and it feels like he's clutching something in his hand.

He opens his eyes and pushes himself up.

Coney Island. Near the SI plant. Convenient, that. Nice of Steve to drop him here.

Suddenly it feels like it has to be a dream. But it wasn't. He knows his memories are real. Mermaids are real. He met one. He-- he slept with one. And God help him, he might be falling for one.

Does Steve feel the same way? How would he know?

Tony looks down at himself. He's still wearing an undershirt and boxers. Great. But he's still holding something in his hand. He turns it over.

It's an abalone shell. It gleams, silvery-bright in the sunshine. It's pretty.

Presents, Steve had said. _Shiny things_. This is how his people court people, he said. Tony gave Steve armor, and Steve gave him a shiny thing.

Some way, somehow, he's going to make this work. They're going to be together again. He knows it.

**Author's Note:**

> [Tumblr post](https://sineala.tumblr.com/post/186321690339/fic-if-the-waters-still-flowing), if you are so inclined.


End file.
